MongoCursor::sort

说明

参数

fields

An array of fields by which to sort. Each element in the array has as
key the field name, and as value either 1 for
ascending sort, or -1 for descending sort.

Each result is first sorted on the first field in the array, then (if
it exists) on the second field in the array, etc. This means that the
order of the fields in the fields array is
important. See also the examples section.